No Dim or Bright headlights, flash to pass workong
 

My truck is an 01 Xlt. Left her with my parents for few days and got it back with the headlights not working. Only running lights come on. I have to hold flash to pass to drive at night.

So far I've replaced the multifunction switch twice, still no luck. Checked all the headlight related fuses, which all seem to be fine. I've replaced the plug that controls the headlights from the switch.

I've never been able to understand a wiring diagram so I'm a bit stuck here. Any help would be appreciated.